The current construction of the medical gas connector assemblies utilized in hospitals and the like for dispensing medical gases such as nitrous oxide, nitrogen, oxygen, etc., is such that there is a serious risk of interchanging the gas-specific portions of each connector assembly after disassembly for purposes of repair or cleaning. The gas-specific portions of the connector assemblies, for gases such as nitrogen, nitrous oxide and air, define diameter-indexed, two stage bores having a first diameter adjacent the entrance end and a smaller diameter further inward from the entrance end. The connector elements at the ends of hoses or gas using devices intended to receive the different gases are also diameter-indexed, i.e. in two steps, with a smaller diameter at the tip and a larger diameter further inwardly from the tip. In each case, the diameters of the hose connectors are complementary to the appropriate diameters of the assemblies into which they are inserted. Once inserted, the appropriate size of nut is threaded onto threads externally of the assembly, to hold the connector in place. Thus the nuts are also gas-specific. The insertion of the connector depresses a plunger located internally of the assembly, and this in turn opens a check-valve to admit gas into the connector.
A standard code has been adopted throughout North America in regard to hand-tightened assemblies for dispensing medical gases, and is known generally as the D.I.S.S. system (Diameter-Index Safety System). Simply stated, the non-interchangeable indexing is achieved by a series of increasing and decreasing diameters. Thus, the gas for which the outermost diameter is largest will also have the smallest innermost diameter. The next gas would have a slightly smaller outer diameter and a slightly larger inner diameter, and so forth. This prevents full insertion of any but the connector for the correct gas using device.
As previously stated, however, the part which defines the two-stage bore of the D.I.S.S. system (as constructed by a number of manufacturers) can itself be removed by unscrewing from a rearward portion of the complete assembly, normally called the rear coupler. All of these portions, called front couplers, have identical threaded bosses with the same thread size and diameter (9/16"--18), and any one of them can be threaded into all of the rear couplers. Thus it occasionally happens that the serviceman, after disassembly for cleaning or repair, inadvertently interchanges the front couplers. In a medical situation, of course, this is highly dangerous, and could result in the administration of the wrong gas to a patient.
It is an aspect of this invention to provide replacement parts compatible with existing installations, and which are constructed in such a way as to eliminate any risk of interchangeability during servicing and repair.
Another aspect of this invention is to provide complete assemblies for new installations, which likewise eliminate the risk of interchangeability during servicing or repair.